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Linking energy efficiency with environmental protection in production - good practice

Vanja Strle

Ljubljana, 23th of February 2011


Energy efficiency

Environmental protection

Use of energy

Use of fuels

Use of energy transferable

mediumsProduction

Enterprise Europe Network

• BETTER ENVIRONMENT

• LOWER COSTS

• BIGGER BENEFITS


Goals


Energy efficiency

Environmental protection

- reduced energy use- reduced use of fuels- reduced use of energy transferable mediums- better working utilisation rate

Lower costs / Better environment

- lower emissions- avoiding of penalties - lower taxes- lower fees- better business occasions

Goals


- reduced energy use- reduced use of fuels

- reduced use of energy transferable mediums- better working utilisation rate

- environmental benefits

OPTIMISATION OF THE PRODUCTION PROCESS

DETAILED KNOWLEDGE OF THE ENERGIES FLOWS

EXAMPLES / Energy intensive industries:

- Production of insulation materials - Lime industry - Cement industry


EXAMPLES / Energy intensive industriesCritical points in this industries are industrial ovens:- the consumption of the fuel- the type of the fuel- the type of the burners- increasing the heat transfer- adding the oxygen in the process- measuring and regulation of the combustion process- fore-heating of the burning air and the oven bed material- isolation- recuperation of the waste heat- good maintaining


1 - Production of insulation materials

• isolation: heat, sound, fire• big consumption of energy source and energy• big production of greenhouse gas emission

• important reducing of fuel consumption in isolated buildings

The ratio - the production of greenhouse emission: production of stone wool : non-isolated buildings, 50 years

1 : 1000


Production of insulating materials - stone wool

Production phases:• raw material preparation• melting• fiberisation of the melt• binder application• product mat formation• curing• cooling• product finishing


Production of insulation materials - stone wool/ melting:

• oven: the coke hot blast cupola,• alumino-silicate rock, dolomite, technological scrap

from stone wool (briquettes – to prevent flow of dust emissions (oven atmosphere, external air), quality of melted material,

disturbing of the flow blowing into the oven),• ~1700 °C,• reductive conditions,• warmed air / O2 - blowing into the hot blast cupola


Production of insulation materials - stone wool/ melting - the energy flow:


entry- energy

melting

wasteenergy

taken away with cooling

taken away with air emissions

possibilities for waste heat use

Production of insulation materials - stone wool/ cooling:


cooling of the coat of hot blast cupola

waste heat

heat is used for drive of absorption

cooling systemroom

heating

cooling of other users

regulation

Production of insulation materials - stone wool/ air emissions from melting:


hot waste air emission

waste heat

warmed air / O2 - blowing

into the hot blast cupola

Production of insulation materials - stone wool/ air emissions from melting:

Different emission pollutants - need different cleaning approaches:

dust – bag filter, electrostatic precipitator, stone wool filter, inorganic gas parameters like oxides of sulphur, oxides of

nitrogen – are affected by the composition of the raw material and the quality of the coke, wet scrubber,

combustible gas parameters as volatile organic compounds, hydrogen sulphide, carbon monoxide – burned in incinerator (thermal oxidation)


Production of insulation materials - stone wool/ air emissions from melting - carbon monoxide:

carbon monoxide – burned in incinerator: it has to be achieved

as much as possible complete burning

CO + ½ O2 = CO2 +


En

minimizing of CO

less needed fuel for incineration

using of waste heat for near users



substanceair emission:

mg/ m3

grams / ton of melted

material

Example for capacity of 20

tons / day

CO 10 – 100.000 30 – 300.000 (0,6 kg – 6.000 kg)/ day

Cupola furnaces (data from EMEP/CORINAR)



Coke hot blast cupola:Reactions Energy

formation /units

C (coke) + ½ O2 = CO ~ 1,1

C (coke) + O2 = CO2 ~ 3,9

CO + ½ O2 = CO2 ~ 2,8

Energy consumed (1,7 units)

C (coke) + CO2 = 2 CO

Production of insulation materials - stone wool:

Other possible measures to reduce the consumption of the fuel and energy and consequently also the air emissions - on the local and global level:

- monitoring of the used fuel (coke, other fuels) - monitoring of the concentration of oxygen, carbon monoxide

and carbon dioxide, which can show the efficiency of the burning

- good isolation of the installations with warmed air and water - the process has to run continuously to prevent heat

oscillations - working start and stop of the hot blast cupola has to be

made progressive


Production of insulation materials - stone wool:

Other possible measures to reduce the consumption of the fuel and energy and consequently also the air emissions - on the local and global level - saving the electric energy => minimizing the operator’s costs and the emissions on the global level:

- high efficiency motors, variable speed drive, - minimizing of the reactive energy losses that cos φ between

the voltage and the current peaks lies permanently between 0,95 – 0,99,

- minimizing of compressed air demand,- Introducing a regular leak control program for compressed

air system,- using of transporters with minimal rubbing


2 - Lime industry

CaCO3 CO2 + CaO

limestone decarbonisation quicklime


raw material – acquisition, preparation

burning in the lime kilnin the range of

800- 1000-1200 -900 /°C

quicklime treatment

slaked lime different granulations

Lime industry

Burning of the limestone in the lime kiln => to use the best combination - the choice of the fuel, type of the kiln, position of the burners, affects on fuel consumption and emissions, as well as on the quality of the product:

- gas, liquid fuel, solid fuel, waste fuels- shaft kilns, rotary kilns, other kilns- internal burners, external burners, special burners for waste

fuel, centralized burners etc


Lime industry

Burning of the limestone in the lime kiln => the right granulation of the limestone in the kiln makes space between particles and this aids:

- better air circulation => reduction of excess air => saving the fuel => less air emissions

- better heat exchange between gases and particles => saving the fuel => less air emissions

- better burning => saving the fuel => less air emissions - better thermal oxidation of CO => less CO emissions is

produced => more energy is released


Lime industry

Burning of the limestone in the lime kiln => the previous cleaning of the limestone:

- better conditions to make free space in the kiln between particles

- less impurities have positive impact on the composition of the air emissions

- easier regulation of the excess air, so not too much heat

escapes with it through the chimney


Lime industry

Burning of the limestone in the lime kiln:


preheating zone

calcining zone

cooling zone

the direction of the limestone flow

~ 800 °C 900°C - 1200°C 900°C => 100°C

preheated airfuel, airemissions to air

Lime industry

Other possible measures to reduce the consumption of the fuel and energy in the lime industry and consequently also the air emissions:

- monitoring of the used fuel - monitoring of the concentration of oxygen, carbon monoxide and

carbon dioxide, which can show the efficiency of the burning- monitoring for controlling of good combustion of the fuel- regulation of burners- good isolation of lime kiln and installations with hot air - the process has to run continuously to prevent heat oscillations - working start and stop of the lime kiln has to be made

progressive


Lime industry

Other possible measures to reduce the consumption of the fuel and energy in the lime industry and consequently also the air emissions:

- saving the electric energy (high efficiency motors, variable speed drivers, minimising of the reactive energy losses that cos φ between the voltage and the current peaks lies permanently between 0,95 – 0,99, minimising of compressed air demand etc.) => minimising of the emissions on the global level

- use of waste hot air coming from preheating zone of lime kiln for the drying


Lime industry

Use of waste hot air from preheating zone of lime kiln for the drying:


preheating zone

calcining zone

cooling zone

the direction of the limestone flow

~ 800 °C 900°C - 1200°C 900°C => 100°C

preheated airfuel, air

emissions to air

DRYING, cleaning-1

production of the sand

washed / wet sand

cleaning-2

Basic steps:


raw material: acquisition, preparation

calcination

clinkering process

cooling of clinker

grinding of clinker, gypsum

and additives

cement

3 - Cement industry

Cement industry: burning


CaCO3 CO2 + CaO

limestone calcination + quicklime1. step

2. step

CaO + (Silica, Al2O3, Fe2O3) Ca-aluminates,

Ca-ferrites, Ca-silicates

clinkering process: clinker

~ 800 - 900°C

~1400°C - 1500°C

Cement industry: fuels for the burning

Fuels used in rotary kiln for the clinker burning:

a) solid fuels: e.g. coal, petcoke

b) liquid fuels: e.g. fuel oil

c) gaseous fuels: e.g. natural gas

d) wastes: e.g. used tyres, waste oils, plastics etc. / the high temperatures and long residence times in the kiln system implies considerable potential for the destruction of organic substances


Cement industry: fuels for the burning


fossil fuel

wastes

- the cost for the fuel- using of natural fuel resources- problems to achieve the reducing of CO2

- the profit for the waste removal- saving the natural fuel resources- less CO2 produced

Additional advantages for using waste as a fuel – comparison with the waste incineration:

- in the rotary kiln are better conditions as in the waste incineration / gas retention times of about 8 seconds at temperatures above 1200°C in the rotary kiln

(waste incineration: minimum 2 seconds at temperatures > 850°C

or minimum 2 seconds at temperatures 1100°C for halogens)

- maximum temperatures achieved in the rotary kiln ~2000 °C- oxidising gas atmosphere in the rotary kiln- uniform burnout conditions in the rotary kiln


Cement industry: wastes as a fuel for the burning process

Aditional advantages for using waste as a fuel – comparison with the waste incineration:

- destruction of organic substances due to the high temperatures at sufficiently long retention time

- sorption of gaseous components (e.g. HF, HCl, SO2) on alkaline reactants

- short retention time of exhaust gases in the temperature range in which PCDD/F can arise

- chemical-minerological incorporation of the heavy metals into the clinker

- complete utilisation of the ashe as a clinker component



Final conclusions about using waste as a fuel in the burning process in cement industry:

saving the natural fuel resources (less fuel used) less CO2 emissions

controlled removal of the waste better environmental conditions for waste removal as in the

waste incineration (less problematic air emissions); of course cleaning device for air emissions has to be used as in waste incineration

complete utilisation of the ash of the burned waste, as a clinker component




Thanks for your attention!

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